Clock-synchronizing system.



H. W. PIDGBON.

CLOCK SYNGHRONIZING SYSTEM.

APPLICATION FILED JULY 29, 1904.

A s SHEETS-SHEET 1.

PATENTED MAY 2, 1905.

PATENTED MAY 2, 1905.

Y. H. w. PIDGEON.

CLOCK SYNUHRONIZING SYSTEM.

APPLICATION FILED JULY 29, 1904.

8 SHEETS-BHBET 2.

N0. 788,.792.- PATENTED MAY 2, 1905. H; W. PIDGEON.

GLOGK SYNCHRONIZING SYSTEM.

APPLICATION FILED JULY 29, 1904.

8 SHEETS-SHEET 3.

No. 788,792. PATENTED MAY 2, 1905. H. W. PIDGEON.

CLOCK SYNOHRONIZING SYSTEM.

APPLICATION FILED JULY 29,1904.

8 SHEETSSHEET 4.

'PATENTED MAY 2 1905 H. W. PIDGEON.

CLOCK SYNGHRONIZING SYSTEM.

APPLIGATION FILED JULY 29, 1904.

B SHEETSSHEET 5.

PATENTED MAY 2, 1905.

H. W PIDGEON CLOCK SYNGHRONIZING SYSTEM.

APPLIOATION FILED JULY 29, 1904.

BSHEETS-SHEET 6.

No. 788,792. PATENTED MAY 2, 1905:

H. W. PIDGEON.

CLOCK SYNOHRONIZING SYSTEM.

APPLICATION FILED JULY 29,1904.

8 SHEETB-SHEET 7.

No; 788,792. PATENTED MAY 2, 1905. H. w. PIDGEON.

CLOCK SYNOHEONIZING SYSTEM.

APPLICATION FILED JULY 29, 1904.

8 SHEETS-SHBET 8.

C?) as 7 Patented May 2, 1905.

UNITED STATES PATENT OFFICE.

HARRY IV. PIDGEON, OF CHICAGO. ILLINOIS, ASSIGNOR TO THE AMERICAN CLOCK COMPANY, OF CHICAGO, ILLINOIS, A CORPORATION OF NFNV JERSEY.

CLOCK-SYNCHRONIZING SAYSTEIVI.

SPECIFICATION forming part of Letters Patent No. 788,792, dated May 2, 1905.

Application filed July 29,1904. Serial No. 218,698.

To all whom it. may concern:

Be it known that I, HARRY \V. PIDGEON, a citizen of the United States, residing at Chicago, in the county of Cook and State of Illinois, have invented certain new and useful Improvements in Clock-Synchronizing Sys- 5 tems, of which the following is a specification.

My invention relates to a clock-synchronizing system of that class utilizing a telephone line-circuit for accurately setting a number of clocks disposed on a telephone-circuit from a master-clock located at the central telephonestation, the circuit line-wires of the telephone system being used for a brief period once every twenty-four hours or other stated period to establish a complete circuit between the master-clock and the secondary clocks.

In carrying out my invention the masterclock is provided with a pair of independent electric circuits each having circuit-closing devices located within the mechanism of the clock and actuated by the latter, one of which circuits, which for convenience 1 shall term the primary master-clock circuit, when closed operates through a relay to break the telephone line-circuittrom the central-switchboard conductors and connect them with a circuit connecting the master-clock and the secondary clocks, while the other circuit, which for convenience I shall term the secondary master-clock circuit, when closed operates through another relay to close the circuit between the master-clock and the secondary clocks, actuating the synchronizing mechanism of the latter, each of said secondary clocks being provided with contact devices in the line of the clockcircuit, which are closed by the mechanism of the secondary clocks just prior to the closing of the clockcircuit by the master-clock in the synchronizizing operation. The master-clock is also provided With mechanism by which after the secondary clocks have been synchronized the connection of the main telephone-circuit with the line-wires of the clock-circuit is broken, and the connection of said main telephone circuitwith the conductors from the central telephone-station is reestablished.

My invention in the best mechanical form 5 thereof which I have as yet devised is illus trated in the accompanying drawings, wherein Figure 1 is a diagrammatic view illustrating a simple telephone-circuit and the relative locations and connections therewith ot' the master and secondary clocks and their circuits. Fig. 2 is a view showing the master-clock and a secondary clock in face elevation with the connecting telephone circuitlines and that branch of the clock-circuit lines passing through the secondary clocks. Fig.

3 is an enlarged front elevational view of the mechanism of the master-clock and its circuit making and breaking devices. Fig. 4c is a 5 side elevational view in section through the dial of the clock of the mechanism shown in Fig. 3. Fig. 5 is a still further enlarged detail face view of a portion of the circuit making and breaking mechanism of the masterclock. Fig. 6 is a view of the same parts shown in Fig. 5 as seen from the opposite side. Fig. 7 is a top plan view of the parts shown in Figs. 5 and 6, including also the clock driving-weights and their actuating mechanism. Fig. 8 is an enlarged edge view of part of the mechanism shown in Fig. 5, viewed in the direction indicated by the arrow in the latter figure, with the clock-dial in section. Fig. 9 is an end elevational view of the mech- 8 anism shown opposite the arrow in Fig. 6. Fig. 10 is a plan view of the contact supporting-arms, separated, oi' the secondary circuit of the master-clock, illustrating their individual formations. Fig. 11 is a view similar to Fig. 3 of the mechanism of one of the secondary clocks and its circuit making and breaking devices. Fig. 12 is a side elevational view, in section through the dial of the clock, of the secondary clock mechanism shown in Fig. 11. Fig. 13 is a top plan view of the principal parts of the secondary-clock mechanism and its circuit making and breaking devices. Fig. 14: is an enlarged detail side elevational view of the circuit making and breaking devices and the synchronizing mechanism ot' the secondary clock. Figs. 15. 16,

and 17 are detail views of parts of the clock actuating mechanism; and Fig. 18 is a detail view, enlarged, of a portion of the secondaryclock mechanism.

As hcreinabove stated, the invention is designed to produce a simple and economical clock-synchronizing system of that type or class which utilizes established circuit linewircs, such as those of a telephone system, the master-clock and the several secondary clocks which are synchronized therefrom being connected by electric circuits of their own with the telephone-circuit and the clocks themselves being equipped with circuit making and breaking devices which, through the agency of suitable relays, interrupt the telephone-circuit from the central station and render it an agent of electrical communication between the individual circuits of the master and secondary clocks for the transmission of an instantaneous electrical impulse from the master-clock to the secondary clocks to actuate the mechanical synchronizing devices of the latter.

Referring to the diagram of Fig. 1, I will first describe the general scheme or plan of the system in outline and will then more specifically describe, by reference to the other views of the drawings, the particular mechanisms for effecting the making and breaking of the several circuits and the synchronizing of the secondary clocks. In this figure, A represents the master-clock, which will preferably be located in the central telephone-station, and B represents an outlying secondary clock. C and D designate, respectively, the outgoing and return lines from the cental or switchboard station, and E and F represent, respectively, the corresponding outgoing and return lines of the telephone-circuit. The meeting ends of the wires C and E and D and E are normally in contact, as shown, thus establishing a complete circuit through the telephone, (indicated at G.) H and I are the two lines of the primary master-clock circuit, said lines having separated contactmints 4A and et8 within the clock mechanism and including in the circuit a battery J and relay K. L and \l are the two lines of the secondary master-clock circuit, said lines having separated contact points 56 and 54 within the clock mechanism and including in the circuit a battery N and relay 0. P and Q represent two lines connecting opposite ends of a relay R with opposite sides of a dynamo S, the line Q being normally broken at q and having an armature q 00- operating with the relay K to close the circuit at (1, but normally retracted by aspring Q2. Opposite the core of the relay R is a pivoted armature 9, normally retracted by a spring r and carrying an insulated bridge r holding the main telephone line-wires E and F normally in contact with the central-station wires C and 1), respectively. T designates a source of electrical energy, such as a dynamo, which is ground (indicated at V) and on the other side has a line wire V leading to a point opposite the core of the relay 0 and provided at such point with an armature we, normally retracted by a spring 10'. X designates a line leading from a point adjacent to the end of the line W by branches X and Xihaving interposed fuses Y and Y to contact-points m and w, opposite the terminal contacts of the main telephone-lines F and E, respectively, and located on the opposite sides of said terminals from the contactpoints of the lines (I and D from the switchboard station.

Referring to the connections of the secondary clocks with the main telephone-circuit, c designates a line tapping either of the wires E F of the main telephone-circuit (the wire E as herein shown) and leading to a contactpoint 76 in the secondary clock. (Z represents another line leading from a co '3perating contact-point 7 9 in the secondary clock, through an electromagnet a, to the ground,(indicated at f.) The electromagnet a when energized actuates through its armature the mechanical devices which effect the setting of the minutehand of the secondary clock to the position simultaneously indicated by the minute-hand of the master-clock.

Once in each twenty-four hours, preferably at a time when the telephone circuit-line is practically idle-say, for instance,three a. m. as the minute-hand of the master-clock approaches the hour the mechanism of the clock brings together the contacts which close the primary master-clock circuit, (represented by the lines H and 1.) This energizes the relaymagnet K, which closes at q the heavier circuit energized by the dynamo S, thus energizing the relay magnet or magnets R and through the connections described disengaging the switchboard connections and establishing the clock-circuit connections with the telephone line-circuit E F. Thereafter and when the minute-hand of the secondary clock B nearly reaches the hour, as indicated by the secondary clock, the mechanism of said clock closes the contacts within the clock mechanism between the wires 0 and d, whereupon the complete clock-circuit through the telephonecircuit, as represented by the lines E E, is established with the exception of the break opposite the relay 0. Thereafter and at the instant the minute-hand of the master-clock points to the hour the mechanism of the master-clock closes the secondary master-clock circuit, (represented by the lines L M.) This,

through the relay-magnet O, connects the wires \V and X, thus establishing the complete clock-circuit and passing a current through the electromagnet c of the secondary clock, thereby actuating the synchronizing mechanism of the latter and setting the secondary clock to the exact time indicated by the master-clock. This having been done, the

connected on one side by a line U with the l mechanism of the secondary clock again breaks the circuit therethrough, at or about which time the mechanism of the master-clock operates to break the primary master-clock circuit whereby the switch-operating circuit 1 Q is also automatically broken, allowing the spring 0" to restore the continuity of the telephone-circuit.

Having thus described in outline the principle on which the system operates, I will next proceed to describe in detail the mecl anisms for effecting the successive operations hereinabove outlined.

The clock which I have chosen with which to illustrate my invention is of the electrically-operated type, wherein a pair of weights are ordinarily raised by electrical impulses passed through an electromagnet located in the clock mechanism, the particular clock herein illustrated being substantially identical with that shown and described in Letters Patent to F. I. Getty, No. 637,454, granted November 21, 1899. I will briefly mention the principal elements of the clock mechanism to the extent that they are related to the mechanism of the present invention, and for a further and more complete description of said clock mechanism reference may be had to the disclosure of the aforesaid patent.

Describing first briefly those parts of the clock mechanism which are common to both the master-clock and the secondary clocks, indicates the clock-case, and 21 the electric battery which furnishes the energy for actuating through electromagnets 22 the weighted arms 23, which, through suitable pawl-andratchet mechanism, effect the turning of the minute-hand shaft or arbor 24, which rotates once in an hour and which carries the minutehand 25. 26 designates the hour-hand sleeve, which is mounted on the minute-hand shaft 24, being geared to the latter by the usual train of speed-reducing gears (indicated in Fig. 8) and carrying the hour-hand 27. 28 designates the shaft of the seconds-hand 29, said shaft having the usual escapement-wheel 31 is the pallet, the arbor 32 of which is connected by the arm 33 with the pendulum 34. These parts, together with the usual connecting and speed regulating gearing, are mounted in a frame 35, which is itself supported by a laterally-offset vertical bracket or support 36, secured to and depending from the top of the clock-case.

Referring now to the master clock, which is more particularly shown in Figs. 3 to 10, inclusive, and describing first the mechanism embodied therein, whereby the making and breaking of the primary and secondary master-clock circuits are affected, 37 designates an arm pivoted at 38 to a bracket 39, secured to one of the uprights of the frame 35, said arm 37 extending transversely of and behind the front upright and carrying at its free end a rigid depending finger 40, which rides over the surface of a disk 41, secured to the back side of a gear 42,which is connected with the gear-train between the minute and hour shafts and is so timed as to rotate once in every twenty-four hours. The disk 41 has a notch or cut-out in its periphery, (shown at 41,) with which the linger 4O cooperates during the synchronizing period. The free end of the arm 37, as best shown in Fig. 4, has a laterally and inwardly projecting insulated elbow-shaped arm 43, which carries at its lower end a laterally-extended contact-pin 44. Secured to the upright 35 below the arm 37 is a horizontally-projecting arm 45, Fig. 6, to the outer end of which is secured an insulated block 46, to the upper end of which is secured an inwardly-extending elastic arm 47, carrying an inclined contact-plate 48, one surface of which is covered by a conducting material, such as platinum, connected with the arm 47, while its other and lower side has a nonconducting surface of ivory or like material. The upper contact-support 43 is connected with the wire I of the primary circuit, while the lower conductor-support 47 is connected through its insulated supporting-block 46 with the other wire, H, of the primary circuit. The contact-points 44 and 48 are held separated by the engagement of the finger with the surface of the disk 41 and can come together only during the interval when the finger 40 is riding over the notch 41 of said disk.

49 designates a bracket-arm secured to the inner side of the front vertical frame member 35 some distance above the pivoted arm 37, as shown in Figs. 5 and 6, the outer end of which arm pivotally supports a pair of suitably-insulated circuit connection-pieces 50 and 51, to the outer ends of which are clamped the ends of the secondary circuit-conductors L and M. Secured to and extending inwardly of the inner ends of the connection-pieces 50 and 51 are contact-arms 52 and 53, respectively. (Shown in inner end view in Fig. 9 and in detail plan view in Fig. 10.) The inner end of the arm 53 is reduced in width and bent downwardly, as shown at 53, and the inner end of the arm 52 is longitudinally slotted for some distance inwardly, as shown at 52 in Fig. 10, thereby producing a forked end. The under side of the arm 53, slightly in rear of its downwardly-bent end 53, is provided with a short depending contact-point 54, while the lower contact-arm 52 has a depending bracket-arm 55, Fig. 6, on its under side, which carries a pair of spring blade-contacts 56, that extend upwardly through the slot of the arm, as shown in Fig. 10, lying directly below the knifeblade contact 54 of the upper arm. On the arbor 28 of the seconds-hand is mounted a small ivory snail-cam 57, Fig. 6, on which rests the tip of the forked end of the arm 52 and the tip of the bent end of the arm 53, it being observed that the contact of the latter on the cam is slightly in rear of the contact of the former with relation to the direction of rotation of the cam, as shown by the arrow.

Referring now to the means for normally holding the contact-arms 52 and 53 separated and unafiected by the rotations of the cam 57 once every minute, 58 designates a verticallydisposed contact-controlling bar, Fig 5, slidably mounted on the outer face of the frame member 35 and suitably guided and confined thereon by pins 59 and 60, playing in vertical slots 61 and 62, respectively, of the bar. On the upper end of said bar are a pair of short laterally-projecting arms 63 and 64, the former carrying an inwardly-projecting pin 65, Fig. 6, which underlies and supports the contactarm 52, and the latter carrying a similar pin 66, which underlies and supports the contactarm 53. The lower end of the bar 58 has a hardened toe-piece 67, the point of which rests upon the periphery of a cam-disk 68, that is secured to the cannon-pinion of the minutehand, and consequently effects a complete rotation once every hour. The periphery of the disk 68 has a series of three successivelydescending steps, (marked 68, 68 and 68, re spectively,) from the foot of which latter a gradual cam-incline 68 leads outwardly to the circular edge of the disk. Thearm 37 is connected to the bar 58, so as to be actuated by the rising and falling movements of the latter, by means of a pin 69 projecting inwardly from the inner face of the bar 58 through a vertical slot 35 in the upright 35 and through a horizontal slot 37 in the arm 37.

Referring next to the secondary clocks and to the mechanism contained therein whereby each of said clocks automatically establishes its own part of the clock-circuit and effects its own synchronizing through the electric impulse sent out from the master-clock, 7O designates a bracket secured to and projecting laterally from the cloclnvork-supporting frame 35 and carrying an electromagnet e, which is interposed in the wire (5 of the secondary-clock circuit, as shown in the diagram Fig. 1. Pivoted to the bracket 70 below and opposite the core of the magnet c is an armature-arm 71, the inner end of which extends to a point below the shaft of the min ute-hand of the clock and carries a laterally-projecting pin 72, extending through a vertical slot 35 in the frame-plate 35. 73 designates a disk mounted on the cannon-pinion, which disk has a notch 73 formed in its periphery and another V-shaped notch, 73 adapted to cooperate with the pin 72 in the synchronizing op eration, said notch 73 being so placed that the action of the pin 72 thereon will set the minute-hand exactly to the predetermined hour at which the synchronizing takes place. Pivoted to the rear side of the frame-plate 35 is a contact-arm 74, carrying adepending linger 75 and at or near its outer end a depending contactpiece 76. This arm 74 is norslot .jects forwardly from the inner end of a short mally pressed downwardly by a light leafspring 77. The arm 7a is connected to the clock-circuit wire 0, leading from one of the line-wires of the telephone-circuit. 78 designates an insulated bracket-arm, which may also be secured to the rear face of the frameplate 35 and which carries an upwardly-extending leaf-spring contact 79, cooperating with the contact-piece 76 to close the circuit. The contact 79 is electrically connected with the line-wire (Z, leading from its supportingbracket 78 to the electromagnet 0.

During the normal operation of the secondary clocks and at all times, excepting a brief period before the synchronizing is to take place, the contacts 76 and 79 are held separated by the following mechanism: 80 designates an upright bar pivoted at its lower end to the armature 71 and at its upper end having a widened head containing an L-shaped In this slot lies a pin 81, which prolever 82, pivoted at 83 and at its rear end carrying an oppositely-projecting pin 84:, which underlies the contact-arm 7 1 just inwardly of the pivot of the latter. A leaf-spring 85 presses against one edge of the bar 80, normally pressing the slotted head of the bar against the pin 81, so that the instant the armature 71 is actuated, thus raising the bar 80, the pin 81 enters the horizontal member of the slot 80*. A spring 86, secured to the under side of the armature 71 and at its lower end connected to the floor of the clock-case or other stationary part, normally draws the armature 71 and bar 80 downwardly, thereby, through the horizontal slot 80, pin 81, short lever 82, and pin 84:, raising the arm 7 1, thereby carrying the contact 76 away from the contact 79, as shown in Fig. 11. 87 designates a disk secured to the back side of a twenty-four-hour wheel 88, Fig. 11, said disk lying in the vertical plane of the linger 75 and having a peripheral notch or cut-out 87, with which the point of said finger cooperates at and shortly around the synchronizing period. 89 designates a vertical strip slidingly supported and guided on the face of theframeplate 35 in the manner already described in connection with the strip 58 of the primary clock. This strip carries at its lower end a toe 90, which cooperates with the periphery of the disk 73, and at its upper end or head has a horizontal notch 89, which receives a pin 91, projecting forwardly from the side of the contact-arm 74:, whereby the latter and the vertical strip 89 are operated in unison. On the inner face of the disk 87 is a pin 92, the function of which is as the. point of the finger 75 nears the notch 87*to engage the edge of the bar 80 and push the same outwardly until the pin 81 passes from the horizontal member of the L-shaped slot 80 to the lower end of the vertical member of said slot. \Vhen this has occurred, a light tension-spring 93,

secured at its lower end to the inner end of the short lever 82, carrying the pin 81, and at its upper end to the stationary framework, raises the inner end of said short lever, thus lowering the pin 84 on the opposite end of said lever out of supporting engagement with the contact-arm 742 and allowing the latter to drop and complete the circuit the instant the toe 90 drops into the notch 73 of the disk 73.

I will now describe the operation of the mechanism as a whole, referring first to the operation of the master-clock mechanism, whereby the telephone-circuit is switched onto the master-clock circuit. The disk 41 rotating at the rate of but one revolution in each twenty-four hours, the arm 37 riding over the periphery of said disk maintains the bar 58 and the contact-arms 52 and 53, supported thereby, raised until the finger 40 reaches the advancing edge of the notch 11, which will occur a few minutes prior to the predetermined time of effecting the synchronizing of the secondary clocks, thus preventing the bar 58 from dropping once every hour as the toepiece 67 reaches and passes over the series of steps 68, 68", and 68 of the cam-disk 68. hen, however, the linger 40 reaches and passes over the advancing proximate edge of the notch 41, the toe-piece 67 will be still resting upon the circular edge of the disk 68 two or three minutes travel back of the step 68. Shortly before the predetermined time for effecting the synchronizing of the secondary clocks say at fifty-eight minutes ten seconds after two a. m.the toe-piece 67 drops down the first step 68 of the disk 68, which drops the arm 37 sufficiently to carry the contactpin 14 onto the upper platinum side of the inclined contact-plate 48. This completes the primary masterclock circuit through the wires H and 1, battery J, and relay-magnet K, thus closing the switch-controlling circuit P Q and through the relay-magnet R actuating the armature r and connecting the telephone line-wires E and F with the circuit-wires X and X of the clock-synchronizing circuit. It will be observed, however, that at this time the latter circuit is open opposite the relaymagnet O. This first drop of the bar 58, while closing the primary circuit-contacts as above described, does not lower the supporting-pins and 66 sufficiently to permit the secondary circuit-contacts 54: and 56 to meet under the action of the cam 57. l/Vhile the toe 67 is still engaged by the first step 68 of the cam, the mechanism of the secondary clocks operates to close the circuit through said clocks, this being brought about as follows: The contacts 76 and 79 being separated, as shown in Fig. 11, during the hour immediately preceding the synchronizing hour, (three a. m. the pin 92 has gradually forced the bar 80 outwardly to bring the pin 81 into the lower end of the vertical member of the slot 80, whereupon the spring 93 has raised the inner end of the short lever 82,

carrying the pin 81, into the upper end of the vertical slot and lowering the pin 84 from beneath the contact-arm 74. This has caused the point of the finger 75 to rest in sliding contact on the periphery of the disk 87 just back of the notch 87 and at the same time has dropped the toe 90 onto the periphery of the disk 73 somewhere between the notches 3" and 7 3 and traveling toward the latter. After the master-clock has established its connection to the telephone-circuit, as already described, but before the master-clock has reached the synchronizing instant-say at fifty-nine minutes six seconds after two a. m., as indicatedby the mastercloek the toe 90 drops into the notch 73, (the finger 75 having meanwhile come above the notch 87, so as to permit the toe 90 thus to drop,) which drops the arm 74 and closes the secondary-clock circuit through the contacts 76 7 9 and electromagnets c. This position of the parts is indicated in Fig. 14:, at which time the variations of the secondary clock from the true time may be anywhere within fifty seconds fast or slow. As indicated in Fig. 14, the secondary clock is within fifty seconds behind the masterclock. The secondary clock is now ready to receive the synchronizing impulse from the master-clock, Thereafter the toe 67 drops from the step 68 onto the step 68". This carries the contact-pin H farther down on the inclined contact-plate &8, still maintaining the contact and holding the master-clock circuit in connection with the telephone-circuit, and at the same time it further lowers the supporting-pins 65 and 66 to such an extent that on the next revolution of the cam 57 as the bent end 53 of the contact-arm 53 rides off the high portion of the cam and while the forked end of the arm 52 is still on the high portion of the cam the contact 54 drops into connection with the contact 56, thereby closing the secondary master-clock circuit L M, energizing the relay-magnet O, and thereby closing the only remaining break in the circuit from the master-clock to the secondary clocks energized by the line U WV, whereby the synchronizing impulse is instantly transmitted to all the secondary clocks on the line, the circuit being closed for the transmission of this impulse at fifty-nine minutes fifty-nine seconds after two a. m., as indicated by the master-clock. One second later, or at three a. m., the end of the contact-arm 52 drops off the high portion of the cam, thus separating the contacts 5 1 and 56 and again opening the clock-circuit opposite the magnet O, and before the contact-arms 53 and 52 have again completed the circuit of the cam 57 the too 67 has dropped onto the lowest step 68, which has carried the contact-pin 4E4 off and below the contact-plate 18, thus breaking the primary master-clock circuit, releasing the armatu re '2', and switching the telephone circuitline E F back onto the central or switchboard- IIO lines C D and cutting out the clock-circuit. This will preferably take place about ten seconds after the synchronizing hour, or at ten seconds after three a. m., in the instance assumed. Thereafter the toe 6T gradually rides up the incline 68, restoring the mechanism of the master-clock to its normal position ready for a repetition of the described operations at the next synchronizing period twentyfour hours ahead. The mechanism of the s'econdary clock when and after the synchronizing impulse has been transmitted therethrough acts as follows: The energizing of the magnets 0 draws the armature 71 upwardly with a sharp quick stroke, whereupon the pin 72, centering with the notch 73", rotates the arbor of the minute-hand in the proper direction and to the proper extent to throw the minute-hand exactly on the hour at that instant indicated by the master-clock.

At the same time the bar is raised until one paireii'ectlng a time contact and the other the pin 81 lies opposite the inner end of the horizontal member of the L-shaped slot 80. Thereupon the leaf-spring 85 instantly acts to thrust said bar inwardly until the pin 81 lies in the outer end of said horizontal slot. The synchronizing impulse being but instantaneous in its duration, the spring 86 then acts to retract the armature 71 and its connected parts, whereby the inner end of the short lever 82, carrying the pin 81, is drawn downwardly against the spring 93, the pin 84: in the opposite end of said lever at the same time forcing upwardly the contact-arm 74, separating the contacts 76 and 79 and carrying the finger 75 out of the notch 87 and slightly above the periphery of the disk 87, the pin 77 on the contact-arm 74 simultaneously lifting the strip 89, thereby carrying the toe 9O slightly above the periphery of the disk 73, thus restoring to normal position, as indicated in Fig. 11, the mechanism of the secondary clock, in which normal position, it will be observed, the members 75 and 90 are held out of contact with their respective eooperating notched disks, whereby they are prevented from constituting a drag or brake on the clock mechanism, such contact with the peripheries of their respective disks being established only within the last hour immediately preceding each synchronizing period, as already described.

The system as hereinabove described and as designed for practical uses will take care of variations of fifty seconds fast or slow per twenty-four hours in the movements of the secondary clocks, which is well within the variations of clocks of average accuracy and reliability. At the same time the entire operation of the system necessitates an interruption of but two minutes in the telephonecircuit, and by making this interruption at an hour when the telephone circuit-line is least busy, such as one of the early hours of the morning, hereinabove assumed for purposes of illustration, practically no inconvenience experienced in the operation of the telephone system. While I have illustratml and described minutely and in detail a complete mechanism for carrying out the purposes of this invention and in practice have found the same to give entirely reliable and satisfactory results, yet it will be understood that numerous variations and modifications in respect to the details of the mechanism would readily suggest themselves to those skilled in this art without departing from the principle and spirit of the invention or sacrificing any of the benefits and advantages thereof. Hence except to the extent indicated in specilie claims the invention is not to be limited to the exactand precise mechanism herein shown.

I claim 1. In a clock-synchronizing system, the combination with a master-clock, of two pairs of electrical contact devices carried thereby,

pair an instantaneous contact, a notched disk rotatable once during the interval between successive synchronizing impulses, a contactearrying member peripherally engaging said notched disk and thereby maintaining said time-contact devices separated except during its engagement with the notch of said disk, and mechanism maintaining said instantaneouscontact devices separated during a portion of the engagement of said contact-carrying member with the notch of said disk. but effecting the closure of said instantaneous contacts at a predetermined instant, substantially as described.

2. In a clock-synchronizing system, the combination with a master-clock, of a pair of time-contact devices carried thereby and a pair of instantaneous-contact devices also carried thereby, a notched disk rotatable once during the interval between successive synchronizing impulses, a contactcarrying member peripherally engaging said notched disk and thereby maintaining said time-contact devices separated except during its engagement with the notch of said disk, a stepped disk whose period of rotation constitutes a factor 01' the period of rotation of said notched disk, a device engaging the periphery of said stepped disk and maintaining said instantaneous contacts separated during a portion of the engagement of said contact-carrying member with the notch of said notched disk. and mechanism effecting the closure of said instantaneous contacts as said device engages the lowermost step of said stepped disk,substantially as described.

3. In a clock -synchronizing system, the combination with a master-clock, of a pair of time-contact devices carried thereby and a pair of instantaneous-contaet devices also carried thereby, a stepped disk mounted on the cannon-shaft, a device engaging the periphery'of said stepped disk and supporting said instantaneous contacts separated except when in en- IIO gagement with the lowermost step of said disk, a notched disk whose period of rotation is a multiple of the period of rotation of said stepped disk and corresponds to the interval between successive synchronizing impulses, a member peripherally engaging said notched disk and supporting one of said time contacts out of engagement with the other except during the engagement of said member with the notch of said disk, and mechanism effecting the closure of said instantaneous contacts upon the engagement of said instantaneous-eon tactsupporting device with the lowermost step of said stepped disk, substantially as described.

4. In a clock-synchronizing system, the combination with a master-clock, of the time contacts i4: and L8 and the instantaneous contacts 55 and 56, the pivoted arm 37 carrying the contact 44 and finger L0, the disk -11 having notch 41 peripherally supporting the arm 37, the stepped disk 68 mounted on the shaft of the cannon-pinion and geared to said notched disk 41, the bar 58 engaging the periphery of said stepped disk and supporting said instantaneous contacts, and the cam 57 serving to close said instantaneous contacts while the finger 40 engages the notch 4:1 and when the bar 58 engages the lowermost step of the stepped disk 68, substantially as described.

5. In a clock-synchronizing system, the combination with a master-clock, of the contact-arms 52 and 53 carrying the instantaneous contacts 56 and 5 respectively, the pivoted arm 37 carrying the. contact a4 and finger 40, the stationary inclined contact-plate 48, the disk 41, havingnotch 41 peripherally supporting the arm 37, the stepped disk 68 mounted on the shaft of the cannon-pinion and geared to said notched disk ll, the bar 58 carrying pins and 66 supporting the contact-arms 52 and 53, respectively, said bar 58 having a lost-motion connection with said arm 37, and the snail-cam 57 mounted on the arbor of the seconds-hand and serving to close the contacts 55 and 56 while the finger 40 engages the notch 41:1 and when the bar 58 engages the lowermost step of the stepped disk 68, substantially as described.

6. In a clock-synchronizing system, the combination with a secondary clock and electrical conductor for synchronizing impulses passed therethrough, of a pair of normally open contacts interposed in said electrical eonductor, means actuated by the clock mechanism whereby said normally open contacts are closed for a brief period in advance of the reception of the synchronizing impulse, a disk mounted on the shaft of the cannon-pinion and having a V-shaped notch in its periphery, an electromagnet interposed in the path of said electrical conductor, an armature having a pin adapted to cooperate with the V-notch of said disk to effect the setting of the minutehand when said magnet is energized by the synchronizing impulse, contact-breaking mechanism connected to said armature and operated on the retracting movement of the latter, and means serving to retract said armature from said magnet except when the latter is energized, substantially as described.

7. In a clock-synchronizing system, the combination with a secondary clock and an electrical conductor for synchronizing impulses passed therethrough, of a fixed contact 7 9 and movable contact 76 interposed in said electrical conductor, a pivoted arm 74 carrying contact 76, a disk 73 mounted on the shaft of the cannonpinion,said disk having a V-shaped notch 73 and also a notch 73, a longitudinallymovable strip 89 engaging the periphery of said disk 73 at its lower end, and at its upper end operatively engaged with said arm 74:, an electromagnet interposed in the path of said electrical conductor, a hinged armature having a pin adapted to cooperate with the notch 73 to effect the setting of the minute-hand when said magnet is energized by the synchronizing impulse, means normally serving to retract said armature, and a lost-motion connection between said armature and said arm 74: normally maintaining said contacts separated, but permitting the closing of said contacts upon the engagement of said strip 89 with the notch 7 3, substantially as described.

8. In a clock -synchronizing system, the combination with a secondary clock and an electrical conductor for synchronizing impulses passed therethwugh, of a fixed contact 79 and movable contact 76 interposed in said electrical conductor, .a pivoted arm-carrying contact 76 and also having a depending finger 7 5, a notched disk 87 with the periphery whereof said finger is adapted to engage, said disk being rotatable once during the period between successive synchronizing impulses, a disk 73 mounted on the shaft of the cannonpinion and having a V-shaped notch 73 and also a notch 73, a longitudinally-inovable strip 89 adapted to engage at its lower end the periphery of disk 73, and at its upper end having pin-and-slot connection with said arm 74, a lever 82 one arm whereof supports said arm 7a, an electromagnet interposed in the path of said electrical conductor, a hinged armature 71 carrying pin 72 adapted to cooperate with notch 73 a bar connected to said armature at its lower end and having an L-slot at its upper end providing a lost-motion connection with the other arm of lever 82, means carried by disk 87 adapted to swing bar 80 in one direction, a spring tending to swing bar 80 in the opposite direction, a spring normally tending to retract said armature, and a spring normally tending to operate lever 82 in a direction to permit closing of said contacts, substantially as described.

HARRY PIDGEON.

itnesses:

SAMUEL N. POND, FREDERICK C. GoonwiN.

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